US20060257085A1 - Fiberoptics, fiberoptic transmission line and optical transmission system - Google Patents

Fiberoptics, fiberoptic transmission line and optical transmission system Download PDF

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US20060257085A1
US20060257085A1 US10/558,630 US55863005A US2006257085A1 US 20060257085 A1 US20060257085 A1 US 20060257085A1 US 55863005 A US55863005 A US 55863005A US 2006257085 A1 US2006257085 A1 US 2006257085A1
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optical fiber
core
chromatic dispersion
refractive index
optical
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Hitoshi Hatayama
Eisuke Sasaoka
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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Assigned to SUMITOMO ELECTRIC INDUSTRIES, LTD. reassignment SUMITOMO ELECTRIC INDUSTRIES, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SASAOKA, EISUKE, HATAYAMA, HITOSHI
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/25—Arrangements specific to fibre transmission
    • H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
    • H04B10/2543—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to fibre non-linearities, e.g. Kerr effect
    • H04B10/2563—Four-wave mixing [FWM]
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G02B6/02219—Characterised by the wavelength dispersion properties in the silica low loss window around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • G02B6/02223—Dual window fibres, i.e. characterised by dispersion properties around 1550 nm and in at least another wavelength window, e.g. 1310 nm
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G02B6/02219—Characterised by the wavelength dispersion properties in the silica low loss window around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • G02B6/02228—Dispersion flattened fibres, i.e. having a low dispersion variation over an extended wavelength range
    • G02B6/02238—Low dispersion slope fibres
    • G02B6/02242—Low dispersion slope fibres having a dispersion slope <0.06 ps/km/nm2
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29371—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion
    • G02B6/29374—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion in an optical light guide
    • G02B6/29376—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion in an optical light guide coupling light guides for controlling wavelength dispersion, e.g. by concatenation of two light guides having different dispersion properties
    • G02B6/29377—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion in an optical light guide coupling light guides for controlling wavelength dispersion, e.g. by concatenation of two light guides having different dispersion properties controlling dispersion around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
    • G02B6/02009—Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G02B6/02219—Characterised by the wavelength dispersion properties in the silica low loss window around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • G02B6/02252—Negative dispersion fibres at 1550 nm
    • G02B6/02257—Non-zero dispersion shifted fibres, i.e. having a small negative dispersion at 1550 nm, e.g. ITU-T G.655 dispersion between - 1.0 to - 10 ps/nm.km for avoiding nonlinear effects
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G02B6/02219—Characterised by the wavelength dispersion properties in the silica low loss window around 1550 nm, i.e. S, C, L and U bands from 1460-1675 nm
    • G02B6/02266—Positive dispersion fibres at 1550 nm
    • G02B6/02271—Non-zero dispersion shifted fibres, i.e. having a small positive dispersion at 1550 nm, e.g. ITU-T G.655 dispersion between 1.0 to 10 ps/nm.km for avoiding nonlinear effects
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
    • G02B6/03644—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - + -

Definitions

  • the present invention relates to an optical fiber, an optical fiber transmission line, and an optical transmission system that are available as an optical transmission line suitable for to an optical transmission for wavelength division multiplexing (WDM).
  • WDM wavelength division multiplexing
  • a WDM optical transmission system is the one that transmits signal light involving a plurality of channels having different wavelengths from each other by way of an optical fiber as a transmission line, and that enables an information transmission of high speed and large capacity.
  • a transmission fiber is an optical fiber mainly composed of silica and having the smallest transmission loss with respect to light in the 1.55 ⁇ m wavelength band.
  • signal light in the 1.55 ⁇ m wavelength band is used.
  • a standard single mode optical fiber having a zero dispersion wavelength in the 1.3 ⁇ m wavelength band has a positive chromatic dispersion in the 1.55 ⁇ m wavelength band.
  • the chromatic dispersion depends greatly on wavelengths, while a waveform of the signal light is deteriorated easily when the chromatic dispersion is large. In addition, the waveform of the signal light is further deteriorated due to an interaction between the chromatic dispersion and non-linear optical phenomena.
  • the following dispersion flattened fiber is proposed: wavelength dependence of chromatic dispersions is reduced over a wide wavelength range, while an absolute value of the chromatic dispersions is controlled at low level, thereby suppressing waveform distortion of signal light caused by the chromatic dispersions (for instance, see Patent Documents).
  • Patent Document 1 U.S. Pat. No. 6,169,837 B1
  • Patent Document 2 Japanese Patent Application Laid-Open No. 8-248251 (EP 0 724 171 A2)
  • the inventors have studied a conventional optical transmission system and a dispersion flattened fiber applied thereto in detail, and as a result, have found problems as follows.
  • a conventional dispersion flattened fiber is designed so that an absolute value of its chromatic dispersion is approximated to zero as nearly as possible.
  • the present invention is made to solve the aforementioned problems, and it is an object to provide an optical transmission system having a structure to reduce variations between wavelengths in chromatic dispersion over a wider wavelength range and also suppress effectively a non-linear optical effect such as four-wave mixing, and to provide an optical fiber and an optical fiber transmission line applicable to this system.
  • An optical transmission system includes an optical fiber transmission line for transmitting signal light having a plurality of channels having different wavelengths from each other, and then this optical fiber transmission line comprises at least one pair of optical fibers having chromatic dispersions having different polarities from each other in the wavelength range of 1460 nm to 1620 nm.
  • optical fibers having chromatic dispersions having different signs from each other are included in the optical transmission system; with respect to any one of the optical fibers, in the wavelength range of 1460 nm to 1620 nm, the optical fiber having a chromatic dispersion whose absolute value is 5 ps/nm/km or more but 10 ps/nm/cm or less and an optical property of 4 ps/nm/km or less in a difference between a maximum value and a minimum value of the chromatic dispersion in the same wavelength range, is applicable.
  • a first optical fiber applicable as a part of the optical fiber transmission line has a dispersion versus wavelength characteristic of an upwardly convex shape in the wavelength range of 1460 to 1620 nm, and has a positive chromatic dispersion
  • a second optical fiber applicable as a part of the optical fiber transmission line has a dispersion versus wavelength characteristic of an downwardly convex shape in the wavelength range, and has a negative chromatic dispersion
  • the first optical fiber has a chromatic dispersion of +5 ps/nm/km or more but +10 ps/nm/km or less in the wavelength range and an optical property of 4 ps/nm/km or less in a difference between a maximum value and a minimum value of the chromatic dispersion in the wavelength range.
  • the second optical fiber has a chromatic dispersion of ⁇ 10 ps/nm/km or more but ⁇ 5 ps/nm/km or less in the wavelength range and optical property of 4 ps/n/km or less in a difference between a maximum value and a minimum value of the chromatic dispersion in the wavelength range.
  • both the first and second optical fibers preferably has a dispersion slope whose absolute value is 0.02 ps/nm 2 /km or less at the wavelength of 1550 nm.
  • the optical fiber transmission line (optical fiber transmission line according to the present invention) composes optical fibers having different chromatic dispersions in polarity from each other, and these optical fibers (optical fiber according to the present invention) have a larger chromatic dispersion as compared with conventional flattened fibers, while they have a smaller chromatic dispersion as compared with standard single mode optical fibers.
  • optical fiber transmission line including the optical fiber, and further optical transmission system including the optical fiber transmission line each can reduce distortion of signal waveforms caused by an occurrence of the chromatic dispersion as compared with standard single mode optical fibers, and can also reduce wavelength dependence of the chromatic dispersion to be occurred, thereby being of extremely great value to be used as a wide range WDM optical transmission system.
  • a difference between the chromatic dispersion at the wavelength of 1460 nm (lower limit wavelength of the wavelength range) and that at the wavelength of 1620 nm (upper limit wavelength of the wavelength range) is preferably 1 ps/nm/km or less.
  • Each of the first and second optical fibers comprises a core region extending along a predetermined axis and a cladding region provided on an outer periphery of the core region.
  • the core region is constructed by: a first core extending a predetermined axis, the first core region having an outer diameter 2 a and a maximum refractive index n 1 ; a second core provided on an outer periphery of the first core, the second core region having an outer diameter 2 b and a refractive index of n 2 lower than that of the first core; and a third core provided on an outer periphery of the second core, the third core region having an outer diameter 2 c and a refractive index of n 3 higher than that of the second core.
  • the cladding region is provided on an outer periphery of the third core, and has a refractive index of n 4 lower than that of the third core.
  • the upper limit of a relative refractive index difference ⁇ ⁇ of the second core with respect to the cladding region is preferably ⁇ 0.3% or less.
  • the lower limit of the relative refractive index difference ⁇ ⁇ of the second core with respect to the cladding region is preferably ⁇ 0.7% or more.
  • the first optical fiber has an effective area A eff 43 ⁇ m 2 or more at the wavelength of 1550 nm, and a relative refractive index difference ⁇ + of the first core with respect to the cladding region is 0.5% or more but 0.6% or less.
  • the second optical fiber has an effective area A eff of 35 ⁇ m 2 or more at the wavelength of 1550 nm, and a relative refractive index difference ⁇ + of the first core with respect to the cladding region is 0.65% or more but 0.80% or less.
  • a eff ⁇ 2 ⁇ ⁇ ⁇ ( ⁇ 0 ⁇ ⁇ E 2 ⁇ r ⁇ ⁇ d r ) 2 ⁇ / ( ⁇ 0 ⁇ ⁇ E 4 ⁇ r ⁇ ⁇ d r ) [ Equation ⁇ ⁇ 1 ]
  • E is the electric field involved in propagation light
  • r is the distance in a radius direction from the center of the core.
  • the first optical fiber preferably has a mode field diameter of 7.5 ⁇ m to 8.5 ⁇ m at the wavelength range, preferably at the wavelength of 1550 nm.
  • an optical fiber transmission line applicable to the optical transmission system according to the present invention can be constructed by a line component unit that composes a pair of first and second optical fibers having the aforementioned structure
  • this optical fiber transmission line may include a plurality of line components each having the same structure as that of the above-described line component.
  • the first optical fiber included in each of the plurality of line components preferably has a mode field diameter of 7.5 ⁇ m to 8.5 ⁇ m in the wavelength range.
  • the optical fiber transmission line constructed by the plurality of line components may have a configuration to be arranged such that the first optical fibers included in the plurality of line components are arranged to be adjacent to each other, and that the second optical fibers included in the plurality of line components are arranged to be adjacent to each other.
  • the optical fiber transmission line comprising the first optical fiber having a positive chromatic dispersion such that its wavelength dependence is reduced over a wide wavelength range of 1460 nm to 1620 nm, and the second optical fiber having a negative chromatic dispersion such that its wavelength dependence is reduced over the wavelength range.
  • each of the first and second optical fibers has a chromatic dispersion of a different polarity, thereby controlling accumulated chromatic dispersion at low level for a whole optical fiber transmission line, while the chromatic dispersion occurs to some extent in each of the first and second optical fibers, thereby controlling effectively non-linear optical effects such as four-wave mixing.
  • FIG. 1 is a diagram showing the constructions of an optical transmission system, a transmitting station, and a receiving station according to the present invention
  • FIG. 2 is a diagram for explaining constructions of optical fiber transmission lines and chromatic dispersion characteristics in the optical transmission system according to the present invention
  • FIG. 3 is a diagram for explaining other constructions of the optical fiber transmission lines in the optical transmission system according to the present invention.
  • FIG. 4 illustrates a sectional structure for explaining a typical structure of an optical fiber and its refractive index profile according to the present invention.
  • FIG. 5 is a table listing specifications for the plurality of samples (samples No. 1 to No. 9 ) with respect to the optical fiber according to the present invention.
  • 10 . . . transmitting station 20 . . . optical fiber transmission line; 30 . . . receiving station; 11 a to 11 n . . . transmitter; 12 . . . multiplexer; 31 . . . demultiplexer; 100 . . . optical fiber; 110 . . . core region; 120 . . . cladding region; 32 a to 32 n . . . receiver; and 250 , 350 . . . fiber module.
  • FIG. 1 is a diagram showing the constructions of an optical transmission system, a transmitting station, and a receiving station according to the present invention.
  • the optical transmission system shown in the area (a) of FIG. 1 , composes a transmitting station 10 for transmitting signal light, an optical fiber transmission line 20 as a transmission medium through which the signal light propagates, and a receiving station 30 for receiving the signal light.
  • a signal input end A of the optical fiber transmission line 20 is connected to a signal output end of the transmitting station 10
  • a signal output end B of the optical fiber transmission line 20 is connected to the signal input end of the receiving station 30 .
  • the transmitting station 10 comprises light sources (TX 1 to TXn) 11 a to 11 n for emitting light beams having wavelengths ⁇ 1 to ⁇ n respectively, and a multiplexer 12 for multiplexing the light beams having the wavelengths ⁇ 1 to ⁇ n emitted from the light sources 11 a to 11 n, and outputs the signal light (WDM signal light), where signal channels of the wavelengths ⁇ 1 to ⁇ n are multiplexed, toward the optical fiber transmission line 20 .
  • WDM signal light signal light
  • the receiving station 30 comprises a demultiplexer 31 for demultiplexing the signal channels of the wavelengths ⁇ 1 to ⁇ n contained in the WDM signal light which propagates through the optical transmission line 20 , and optical receivers (RX 1 to RXn) 32 a to 32 n for receiving the light beams having the wavelengths ⁇ 1 to ⁇ n and demultiplexed by the demultiplexer 31 respectively.
  • a demultiplexer 31 for demultiplexing the signal channels of the wavelengths ⁇ 1 to ⁇ n contained in the WDM signal light which propagates through the optical transmission line 20
  • optical receivers (RX 1 to RXn) 32 a to 32 n for receiving the light beams having the wavelengths ⁇ 1 to ⁇ n and demultiplexed by the demultiplexer 31 respectively.
  • the optical fiber transmission line 20 is constructed by at least one pair of optical fibers having chromatic dispersions having different polarities from each other in a wavelength range of 1460 nm to 1620 nm.
  • the transmission line 20 has a structure such that a first optical fiber 200 having a positive chromatic dispersion in the wavelength range of 1460 nm to 1620 nm is fusion-spliced with a second optical fiber 300 having a negative chromatic dispersion in the wavelength range.
  • Each of the optical fibers 200 , 300 has a chromatic dispersion whose absolute value is 5 ps/nm/km or more but 10 ps/nm/km or less in the wavelength range.
  • the first optical fiber 200 has a dispersion versus wavelength characteristic of an upwardly convex shape in the wavelength range.
  • the first optical fiber 200 has a positive chromatic dispersion of +5 ps/nm/km to +10 ps/nm/km in the wavelength range, and an optical property of 4 ps/nm/km or less in a difference between the maximum value and the minimum value of the chromatic dispersion in the wavelength range.
  • the second optical fiber 300 has a dispersion versus wavelength characteristic in a downwardly convex shape.
  • the second optical fiber 300 has a chromatic dispersion of ⁇ 10 ps/nm/km or more but ⁇ 5 ps/nm/km or less in the wavelength range, and an optical property of 4 ps/nm/km or less in a difference between the maximum value and the minimum value of the chromatic dispersion in the wavelength range.
  • each of the first and second optical fibers 200 , 300 preferably has a dispersion slope of 0.02 ps/nm 2 /km or less in absolute value at the wavelength of 1550 nm.
  • the optical fiber transmission line 20 comprises the first and second optical fibers 200 , 300 having chromatic dispersions different in polarity from each other.
  • These first and second fibers 200 , 300 have a larger chromatic dispersion as compared with that of conventional flattened fibers (substantially zero in a wavelength range for use), while they have a smaller chromatic dispersion as compared with that of standard single mode optical fibers (approximately 21 ps/nm/km at the wavelength of 1620 nm).
  • the optical fiber transmission line 20 constructed by the first and second optical fibers 200 , 300 performs characteristics of chromatic dispersion as shown in graph G 230 in the area (c) of FIG. 2 .
  • the optical transmission system including the optical fiber transmission line 20 having the aforementioned characteristics of chromatic dispersion can reduce distortion caused by an occurrence of the chromatic dispersion as compared with standard single mode optical fibers (accumulated chromatic dispersion viewed from the whole optical fiber transmission line is small), and can also reduce wavelength dependency of occurred chromatic dispersions, which enables usage as a wide-band WDM optical transmission system.
  • a difference between the chromatic dispersion at the wavelength of 1460 nm (lower limit wavelength of the wavelength range) and that at the wavelength of 1620 nm (upper limit wavelength of the wavelength range) is preferably 1 ps/nm/km or less.
  • the whole optical fiber transmission line 20 has a chromatic dispersion of 1 ps/nm/km or less in the range of 1460 nm to 1620 nm.
  • the optical fiber transmission line 20 by a pair of the first and second optical fibers 200 , 300 (line components), each of which may contain a plurality of line components having the same structure as that of such a line component.
  • the optical fiber transmission lien 20 may also be arranged such that first optical fibers 210 , 220 contained in the plurality of line components are adjacent to each other, and that second optical fibers 310 , 320 contained in the plurality of line components are adjacent to each other.
  • deterioration of transmission characteristics caused by non-linear optical effects can be effectively suppressed by controlling the number of changes in polarity of the chromatic dispersion to be occurred along the longitudinal direction of the optical fiber transmission line 20 .
  • the optical fiber transmission line 20 may have a construction to function one of the first and second optical fibers 200 , 300 as an optical transmission line and arrange the other on the transmission line to be provided as a module.
  • the optical fiber transmission line 20 constructed by a fiber module 350 including the first optical fiber 200 and second optical fiber 300 is shown in the area (a) of FIG. 3 .
  • the fiber module 350 has a container for storing the second optical fiber 300 wound at a diameter d. This container is provided with a connector 305 for connecting optically a signal input end of the second optical fiber 300 and a signal output end of the first optical fiber 200 , and a connector 306 for connecting optically a signal output end of the second optical fiber 300 and a signal input end of a receiving station 20 .
  • an optical fiber transmission line 20 constructed by a fiber module 250 including a first optical fiber 200 and a second optical fiber 300 is shown in the area (b) of FIG. 3 .
  • the fiber module 250 has a container for storing the first optical fiber 200 wound at d in diameter. This container is provided with a connector 205 for connecting optically a signal input end of the first optical fiber 200 and a signal output end of a transmitting station, and a connector 206 for connecting optically a signal output end of the first optical fiber 200 and a signal input end of the second optical fiber 300 .
  • chromatic dispersion can be performed by a refractive index profile as shown in the area (b) of FIG. 4 .
  • FIG. 4 is a view illustrating a sectional structure from a typical structure of an optical fiber according to the present invention and its refractive index profile.
  • first and second optical fibers 200 , 300 each have a core region 21 , and a cladding region 22 provided on an outer periphery of the core region 21 and having a refractive index of n 4 .
  • the core region 21 comprises: a first core 21 a extending along a predetermined axis, having an outer diameter 2 a and having a refractive index n 1 (>n 4 ); a second core 21 b provided on an outer periphery of the first core 21 a, having an outer diameter 2 b and having a refractive index n 2 ( ⁇ n 1 , n 4 ); and a third core 21 c provided on an outer periphery of the first core 21 b, having an outer diameter 2 c and having a refractive index n 3 ( ⁇ n 1 , >n 2 , n 4 ).
  • a relative refractive index difference ⁇ + of the first core 21 a, a relative refractive index difference ⁇ ⁇ of the second core 21 b, and a relative refractive index difference ⁇ r of the third core 21 c with respect to the cladding region 22 are provided with the following equations. ⁇ + ⁇ (n 1 ⁇ n 4 )/n 1 ⁇ 100 ⁇ ⁇ ⁇ (n 2 ⁇ n 4 )/n 2 ⁇ 100 ⁇ r ⁇ (n 3 ⁇ n 4 )/n 3 ⁇ 100 [Equation 2]
  • a refractive profile 290 of an optical fiber corresponding to each of the first and second optical fibers 200 , 300 shown in the area (a) of FIG. 4 is shown in the area (b) of FIG. 4 .
  • a region 291 represents a refractive index at each area on line L of the first core 21 a
  • a region 292 represents a refractive index at each area on line L of the first core 21 b
  • a region 293 represents a refractive index at each area on line L of the third core 21 c
  • a region 294 represents a refractive index at each area on line L of the cladding region 22 .
  • FIG. 5 is a table listing specifications for nine types of optical fibers as the samples for the optical fiber according to the present invention.
  • optical fibers of Types 1 to 5 are samples for the first optical fiber 200 having a positive chromatic dispersion in the wavelength range of 1460 nm to 1620 nm
  • optical fibers of Types 6 to 9 are samples for the second optical fiber 300 having a negative chromatic dispersion in the wavelength range.
  • all the optical fibers of Types 1 to 9 corresponding to any one of the first and second optical fibers 200 , 300 have a sectional structure and refractive index profile shown in FIG. 4 .
  • the optical fiber of Type 1 corresponds to the first optical fiber 200 , the outer diameter 2 a of the first core is 7.92 ⁇ m, the outer diameter 2 b of the second core is 12.29 ⁇ m, and the outer diameter of the third core is 18.20 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.65%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.7%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 1 has a chromatic dispersion of 7.74 ps/nm/km, a dispersion slope of ⁇ 0.002 ps/nm 2 /km, and an effective area A eff of 37.55 ⁇ m 2 , and a mode field diameter MFD of 6.87 ⁇ m. Additionally, the optical fiber of Type 1 has the chromatic dispersions of 6.71 ps/nm/km and 7.09 ps/n/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.41 ⁇ m.
  • the optical fiber of Type 2 corresponds to the first optical fiber 200 , the outer diameter 2 a of the first core is 7.97 ⁇ m, the outer diameter 2 b of the second core is 13.54 ⁇ m, and the outer diameter of the third core is 19.20 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.65%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.5%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 2 has a chromatic dispersion of 8.38 ps/nm/km, a dispersion slope of 0.007 ps/nm 2 /km, and an effective area A eff of 38.06 ⁇ m 2 , and a mode field diameter MFD of 6.97 ⁇ m. Additionally, the optical fiber of Type 2 has the chromatic dispersions of 6.67 ps/nm/km and 8.40 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.40 ⁇ m.
  • the optical fiber of Type 3 also corresponds to the first optical fiber 200 , the outer diameter 2 a of the first core is 6.66 ⁇ m, the outer diameter 2 b of the second core is 16.98 ⁇ m, and the outer diameter of the third core is 22.20 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.77%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.3%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 3 has a chromatic dispersion of 8.53 ps/nm/km, a dispersion slope of 0.024 ps/nm 2 /km, and an effective area A eff of 31.37 ⁇ m 2 , and a mode field diameter MFD of 6.43 ⁇ m. Additionally, the optical fiber of Type 3 has the chromatic dispersions of 5.32 ps/nm/km and 9.64 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.44 ⁇ m.
  • the optical fiber of Type 4 also corresponds to the first optical fiber 200 , the outer diameter 2 a of the first core is 8.42 ⁇ m, the outer diameter 2 b of the second core is 13.96 ⁇ m, and the outer diameter of the third core is 19.80 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.57%
  • the relative refractive index difference ⁇ + of the second core is ⁇ 0.5%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 4 has a chromatic dispersion of 8.06 ps/nm/km, a dispersion slope of 0.003 ps/nm 2 /km, and an effective area A eff of 43.84 ⁇ m 2 , and a mode field diameter NED of 7.44 ⁇ m. Additionally, the optical fiber of Type 4 has the chromatic dispersions of 6.71 ps/nm/km and 7.79 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.46 ⁇ m.
  • the optical fiber of Type 5 also corresponds to the first optical fiber 200 , the outer diameter 2 a of the first core is 8.42 ⁇ m, the outer diameter 2 b of the second core is 13.96 ⁇ m, and the outer diameter of the third core is 19.80 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.54%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.5%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 5 has a chromatic dispersion of 8.35 ps/nm/km, a dispersion slope of 0.002 ps/nm 2 /km, and an effective area A eff of 45.47 ⁇ m 2 , and a mode field diameter MFD of 7.57 ⁇ m. Additionally, the optical fiber of Type 5 has the chromatic dispersions of 7.04 ps/nm/km and 8.00 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.48 ⁇ m.
  • the optical fiber of Type 6 corresponds to the second optical fiber 300
  • the outer diameter 2 a of the first core is 6.83 ⁇ m
  • the outer diameter 2 b of the second core is 10.21 ⁇ m
  • the outer diameter of the third core is 16.08 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.76%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.7%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 6 has a chromatic dispersion of ⁇ 7.95 ps/nm/km, a dispersion slope of ⁇ 0.021 ps/nm 2 /km, and an effective area A eff of 35.24 ⁇ m 2 , and a mode field diameter MFD of 6.65 ⁇ m. Additionally, the optical fiber of Type 6 has the chromatic dispersions of ⁇ 6.28 ps/nm/km and ⁇ 9.22 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.39 ⁇ m.
  • the optical fiber of Type 7 corresponds to the second optical fiber 300 , the outer diameter 2 a of the first core is 6.64 ⁇ m, the outer diameter 2 b of the second core is 10.87 ⁇ m, and the outer diameter of the third core is 16.52 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.77%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.5%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 7 has a chromatic dispersion of ⁇ 7.92 ps/nm/km, a dispersion slope of ⁇ 0.019 ps/nm 2 /km, and an effective area A eff of 35.11 ⁇ m 2 , and a mode field diameter MFD of 6.69 ⁇ m. Additionally, the optical fiber of Type 7 has the chromatic dispersions of ⁇ 6.52 ps/nm/km and ⁇ 9.06 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.40 ⁇ m.
  • the optical fiber of Type 8 also corresponds to the second optical fiber 300 , the outer diameter 2 a of the first core is 6.18 ⁇ m, the outer diameter 2 b of the second core is 12.27 ⁇ m, and the outer diameter of the third core is 17.40 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.81%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.3%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 8 has a chromatic dispersion of ⁇ 7.79 ps/nm/km, a dispersion slope of ⁇ 0.020 ps/nm 2 /km, and an effective area A eff of 33.17 ⁇ m 2 , and a mode field diameter MFD of 6.58 ⁇ m. Additionally, the optical fiber of Type 8 has the chromatic dispersions of ⁇ 6.70 ps/nm/km and ⁇ 9.28 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.39 ⁇ m.
  • the optical fiber of Type 9 also corresponds to the second optical fiber 300 , the outer diameter 2 a of the first core is 7.13 ⁇ m, the outer diameter 2 b of the second core is 11.53 ⁇ m, and the outer diameter of the third core is 17.60 ⁇ m.
  • the relative refractive index difference ⁇ + of the first core is 0.69%
  • the relative refractive index difference ⁇ ⁇ of the second core is ⁇ 0.5%
  • the relative refractive index difference ⁇ r of the third core is 0.3%.
  • this optical fiber of Type 9 has a chromatic dispersion of ⁇ 7.75 ps/nm/km, a dispersion slope of ⁇ 0.016 ps/nm 2 /km, and an effective area A eff of 40.52 ⁇ m 2 , and a mode field diameter MFD of 7.11 ⁇ m. Additionally, the optical fiber of Type 9 has the chromatic dispersions of ⁇ 6.25 ps/nm/km and ⁇ 8.47 ps/nm/km at the wavelengths of 1460 nm and 1630 nm, respectively. Then, the cutoff wavelength ⁇ c is 1.48 ⁇ m.
  • the relative refractive index difference ⁇ ⁇ of the second core 21 b with respect to the cladding region 22 is ⁇ 0.7% or more but ⁇ 0.3% or less.
  • an effective area A eff of 43 ⁇ m 2 or more is provided at the wavelength of 1550 nm, and the relative refractive index difference ⁇ + of the first core 21 a with respect to the cladding region 22 is 0.5% or more but 0.6% or less.
  • these optical fibers of Types 1 to 9 each have a transmission loss of 0.21 dB/km or less, a micro-bending loss of 10 dB/m or less when it is bent at a diameter of 20 mm, and a polarization mode dispersion of 0.25 dB ⁇ km ⁇ 1/2 or less at the wavelength of 1550 nm.
  • an optical fiber transmission line applicable to the optical transmission system according to the present invention can be constructed by a line component unit that comprises a pair of first and second optical fibers having the aforementioned structure
  • this optical fiber transmission line may include a plurality of line components each having the same structure as that of the above-described line component.
  • the first optical fiber 200 included in each of the plurality of line components preferably has a mode field diameter of 7.5 ⁇ m to 8.5 ⁇ m in the above-described wavelength range.
  • the invention is applied to an optical transmission system that enables to reduce variations between wavelengths in chromatic dispersion over a wide wavelength range, and suppress non-linear optical effects.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
US10/558,630 2003-07-11 2004-07-09 Fiberoptics, fiberoptic transmission line and optical transmission system Abandoned US20060257085A1 (en)

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JP2003273575A JP2005031581A (ja) 2003-07-11 2003-07-11 光ファイバ、光ファイバ伝送路及び光伝送システム
JP2003-273575 2003-07-11
PCT/JP2004/009840 WO2005006041A1 (ja) 2003-07-11 2004-07-09 光ファイバ、光ファイバ伝送路及び光伝送システム

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Publication number Priority date Publication date Assignee Title
US6169837B1 (en) * 1997-12-05 2001-01-02 Sumitomo Electric Industries, Ltd. Dispersion-flattened optical fiber

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CA1248386A (en) * 1982-03-11 1989-01-10 Leonard G. Cohen Quadruple-clad optical fiberguide
US5684909A (en) * 1996-02-23 1997-11-04 Corning Inc Large effective area single mode optical waveguide
AU724900B2 (en) * 1996-07-01 2000-10-05 Corning Incorporated Optical fiber with tantalum doped clad
TW451088B (en) * 1999-04-16 2001-08-21 Sumitomo Electric Industries Optical fiber and optical transmission line including the same
JP5028706B2 (ja) * 2000-05-01 2012-09-19 住友電気工業株式会社 光ファイバおよび光伝送システム
JP2001166173A (ja) * 1999-12-13 2001-06-22 Sumitomo Electric Ind Ltd 光ファイバ
JP2002365462A (ja) * 2001-06-12 2002-12-18 Furukawa Electric Co Ltd:The 光通信リンク
FR2828939B1 (fr) * 2001-08-27 2004-01-16 Cit Alcatel Fibre optique pour un systeme de transmission a multiplexage en longueurs d'onde
JP2003188822A (ja) * 2001-10-10 2003-07-04 Furukawa Electric Co Ltd:The 光伝送路およびその光伝送路を用いた光伝送システム
JP2003255169A (ja) * 2002-03-04 2003-09-10 Furukawa Electric Co Ltd:The 光ファイバおよびその光ファイバを用いた光伝送路ならびに光伝送リンク
FR2842610B1 (fr) * 2002-07-18 2004-11-12 Cit Alcatel Fibre optique a gestion de dispersion

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6169837B1 (en) * 1997-12-05 2001-01-02 Sumitomo Electric Industries, Ltd. Dispersion-flattened optical fiber

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